1. Field of the Invention
The invention relates to a process for preparing high-purity hexachlorodisilane by distillation.
2. Description of the Related Art
EP-A 1 264 798 describes the preparation of hexachlorodisilane from the offgases from the deposition of polycrystalline silicon by distillative removal from the other chlorosilanes and process gases. GB 923 784 describes the preparation of hexachlorodisilane by thermally cracking trichlorosilane within a temperature range from 200 to 600° C., wherein the reaction must be performed under a protective gas or under hydrogen gas. DE 11 42 848 likewise describes obtaining high-purity hexachlorodisilane by heating trichlorosilane to 200 to 1000° C. in an electron burner. This reaction too is performed under protective gas or using hydrogen as the transport gas. WO-A 06109427 describes the removal of silanol from hexachlorodisilane by treatment with activated carbon, followed by a distillation. In Ultrareine Stoffe No. 4(1994), V.A. Schaligin et al. state, that in a distillation of hexachlorodisilane, the boiling point of the product should not be exceeded since a decomposition of the hexachlorodisilane would otherwise proceed.